7/8 lineset on a 5 ton system

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Originally Posted by craig1

Its actually more complicated than that. When you reduce capacity, you reduce the work being done by the compressor, which in turn reduces its amp draw. So even if the restricted line causes a 3% capacity reduction, efficiency reduction might only be 1% or even nothing.

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under sized suction lines cause a capacity loss and hi velocity.....

Quote:

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Originally Posted by craig1

Its actually more complicated than that. When you reduce capacity, you reduce the work being done by the compressor, which in turn reduces its amp draw. So even if the restricted line causes a 3% capacity reduction, efficiency reduction might only be 1% or even nothing.

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I was just pointing out that you do in fact lose efficiency, not attempting to exactly quantify the efficiency loss.

Continuing the discussion though, when you are dealing with total system capacity losses due to pressure losses, and other issues within the system, the electrical consumption per btuh of net refrigeration usually doesn't go down, or even stay the same.
Typically it will go up.

Either way, in most instances the small efficiency loss, due to the small capacity loss incurred by having the smallest recommended vapor line for the application, isn't worth the cost of replacing the refrigerant lines.

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Originally Posted by carmon

under sized suction lines cause a capacity loss and hi velocity.....

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Originally Posted by mark beiser

I was just pointing out that you do in fact lose efficiency, not attempting to exactly quantify the efficiency loss.

Continuing the discussion though, when you are dealing with total system capacity losses due to pressure losses, and other issues within the system, the electrical consumption per btuh of net refrigeration usually doesn't go down, or even stay the same.
Typically it will go up.

Either way, in most instances the small efficiency loss, due to the small capacity loss incurred by having the smallest recommended vapor line for the application, isn't worth the cost of replacing the refrigerant lines.

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Quote:

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Originally Posted by craig1

Its actually more complicated than that. When you reduce capacity, you reduce the work being done by the compressor, which in turn reduces its amp draw. So even if the restricted line causes a 3% capacity reduction, efficiency reduction might only be 1% or even nothing.

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Yes, it is more complicated than that. Remember pump laws and fan laws state that when you block flow, the amp draw is reduced. How much would be hard to determine and you may gain/lose efficiency or stay the same. Calculations for this stuff are just estimations, and you would really have to test it and get real numbers and plot an efficiency curve to find out. But with such a small difference, it doesn't really make sense to worry about. There are a lot of other things that can make a bigger difference, one being orientation and location of the condenser to minimize solar radiation effects which can raise the head pressure considerably and drop efficiency.

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Originally Posted by dijit

Yes, it is more complicated than that. Remember pump laws and fan laws state that when you block flow, the amp draw is reduced. How much would be hard to determine and you may gain/lose efficiency or stay the same. Calculations for this stuff are just estimations, and you would really have to test it and get real numbers and plot an efficiency curve to find out. But with such a small difference, it doesn't really make sense to worry about. There are a lot of other things that can make a bigger difference, one being orientation and location of the condenser to minimize solar radiation effects which can raise the head pressure considerably and drop efficiency.

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Solar radiation doesn't have much effect either. unless the condenser is on a roof, or other surface that is reflecting both radiant heat and convection heat.